Chlorination byproducts of 4,4′-methylene dianiline(MDA) and their mutagenicity

Abstract

A mutagenicity study was carried out on 4,4′-methylene dianiline(MDA) an epoxy resin hardener and chlorinated MDA using an Ames Salmonella/microsome assay. As reaction products of MDA with chlorine in the water six spots were observed by thin layer chromatograph(TLC) and high performance liquid chromatography(HPLC) analysis revealed eighteen peaks on the HPLC chromatogram. MDA exhibited mutagenic activity for strain TA100 in the presence of S9 mix. In the mutagenicity test of chlorinated MDA corresponding to 7.8∼250 μg/plate, at 250 μg/plate the specimen showed mutagenic activity for strain TA98 without S9 mix, but more diluted specimens had no mutagenicity. At 31 and 250 μg/plate, the specimen showed weak mutagenic activity for the strain TA98 in the presence of S9 mix. The strain TA100 without S9 mix was killed on the culture plate with 250 μg/plate. However strong mutagenicity such as net revertant colonies 1270 per plate was obtained with the diluted specimen of 7.8 μg/plate. At 31 μg/plate, the specimen showed mutagenic activity for the strain TA100 with S9 mix. The mutagenicity test of five fractionated specimens from the TLC analysis, spot No. 1 and No. 2 showed no mutagenicity for strain TA98 and TA100 with and without S9 mix. The specimen of Spot No. 3 exhibited weak mutagenic activity for strain TA98 without S9 mix, the specimen of spot No. 4 at 125 μg/plate showed mutagenicity for strain TA98 and TA100 with and without S9 mix, and diluted samples showed high mutagenic activity for strain TA100 with and without S9 mix. Several newly identified mutagenic substances were found to be produced by the chlorination of MDA. GC/MS analysis of chlorinated MDA revealed eleven compounds on the chromatogram. Benzaldehyde, benzoquinones and chloroanilines were identified. However, the structural formula of the highly mutagenic substances could not be determined by GC/MS.